Sexing A Dinosaur

ZOMG. Get your mind out of the gutter. We would never write about dinosaur sexxxytime. We are not that kind of blog. Well, except that one time. At band camp. No. What we are talking about is exciting news in the field of paleontology: finally, scientists believe they can accurately differentiate between male and female dinosaurs.1

Oh what, you thought that was something we could do already? No, it is not. Hey, science can’t even decide if Brontosaurus actually existed, so it really shouldn’t come as a surprise that we’re not real clear about the sex of the dinosaur skeletons we’ve unearthed.

In fact, even this study really only applies to smaller, feathered dinosaurs. Because those are the ones that shake their tail feathers. Oh hah. You think we are joking, but we are not!

Scientist have been studying the Romeo and Juliet of dinosaurs, a pair of embracing oviraptorosaurs found in the Gobi Desert in the ’90s. But, while the couple appeared to be embracing, discovering the sex of a dinosaur is hard work.

The fossil remains of two oviraptorosaurs — nicknamed ‘Romeo and Juliet’ — were reported in 2001. Credit: Amanda Kelly

Researchers announced in Nature earlier this month that the pair did show anatomical differences, suggesting that the totally fictional romantic backstory made up by paleontologists was a definite possibility.2

So after decades of research, we have finally figured out which dino is Romeo. Romeo is the one that shakes it like a polaroid picture. Yep! Dinosaurs have what scientists call “chevrons” blade-like bones which jut down from the vertebrae near the base of the tail. The chevrons provide attachment for muscles and tendons. Well, it’s likely that Romeo had longer and broader chevrons, so that he could shake what his mama gave him in a manly display of plumage and courtship.

See, they are totally different!

What, not clear enough for you?! Fine:

Courtesy of Nature

So you may be asking yourself, how do they know that it was the manly Romeo doing all the shaking? Well, researchers basically compared it to the role of butt muscles in modern birds. Fine, don’t believe us, go read all the big words yourselves!

So, while intriguing, this battle for the sexes really is limited to tiny feathery dinosaurs – oviraptorosaurs are about the same size as a turkey.3 In the paper, researchers explicitly say that this will not apply to avian dinosaurs. So all you oviraptorosaurs collectors grab a caliper and get to measuring your chevrons so that you know if your dino skeleton should be carrying a purse.

The pair have been called Romeo and Juliet for years, despite having no idea of the couples’ sex, or for that matter gender expression. Damned heteronormative bias! ↩

Also their name is awesome: Egg Thieving Lizard, basically because a long time ago an oviraptorosaurs was found near the nest of a different species of dinosaur. Except we screwed up and it was probably just protecting its own nest. At least according to this dinosaur coloring book. ↩